Delhi, known locally as Dilli and also by the official name National Capital Territory of Delhi (NCT), is the second-largest metropolis in India. With over 17.3 million residents, it is the eighth largest metropolis in the world by population. The name Delhi is often also used to include some urban areas near the NCT, as well as to refer to New Delhi, the capital of India, which lies within the NCT.

Public transportation in the city is provided by buses, auto rickshaws and a metro rail system respectively.

Buses are the most popular means of transport catering to about 60% of the total demand. The state-owned Delhi Transport Corporation is a major bus service provider for the city.

The Delhi Metro, a mass rapid transit system built and operated by Delhi Metro Rail Corporation (DMRC), serves many parts of Delhi. As of 2007, the metro consists of three lines with a total length of 65 km (40 miles) and 59 stations while several other lines are under construction. Phase-II of the network is under construction and will have a total length of 128 km. It is expected to be completed by 2010 with the final phases being completed by 2020 creating a network spanning 413.8 km, longer than that of the London Underground.

Despite public transportation, motorization in Delhi is increasing at an alarming rate. The number of motor vehicles has increased from 5.4 lakhs in 1981 to 51 lakhs by the end of the 20th Century and is increasing at the rate of 6.21 per annum. Delhi has more motor vehicles than Mumbai, Calcutta and Chennai put together. The result is extreme congestion on Delhi roads, ever slowing speeds, increase in road accidents fuel wastage and environmental pollution with motorized vehicles alone contributing to about two thirds of the atmospheric pollution.